Laparoscopy is a safe and useful method for examining the local extent and regional spread of disease in patients with gastric cancer. Peritoneal dissemination remains a frequent type of recurrence after surgical treatment. The aim of this study was to determine the prognostic value of intraperitoneal free cancer cells (IFCCs) detected by laparoscopic peritoneal lavage. Forty-nine patients with advanced gastric cancer underwent laparoscopy with cytologic examination for staging. Peritoneal lavage was performed when ascites was not present. Aspirated fluid from the peritoneal cavity was centrifuged and subjected to cytologic examination using Giemsa and Papanicolaou staining methods. Patients were surgically treated and followed for a minimum of 5 years. IFCCs were detected in 41% of the patients. In eight cases (16.3%) laparoscopy revealed carcinomatosis and/or multiple liver metastases, so laparotomy was not performed. Patterns of recurrence after curative resection included the following: peritoneal (n = 3), local (n = 4), liver (n = 1), and other (n = 1). All patients who tested positive for IFCCs had peritoneal recurrence. The absence of IFCCs was associated with improved overall survival (21 months for a 95% confidence interval of 7.4 to 34.6 vs. 4 months for a 95% confidence interval of 2.4 to 5.6). Overall survival adjusted for type of resection also demonstrated a favorable outcome for patients who were negative for IFCCs. The following conclusions were drawn: (1) laparoscopic peritoneal lavage cytology may be useful in identifying patients at high risk for peritoneal relapses and may alter treatment, and (2) lFCCs provide additional prognostic information in patients with gastric cancer.